Part 1: Making the Cookie Dough

Step 1: Prepare the Dry Ingredients and Melt the Chocolate

• In a medium bowl, whisk together the 1 ½ cups of all-purpose flour, ⅔ cup of Dutch-process cocoa powder, 1 teaspoon of baking soda, and ½ teaspoon of salt. Whisking thoroughly ensures the leavening is evenly distributed. Set aside.
• In a separate, microwave-safe bowl, melt the 4 ounces of semi-sweet or bittersweet chocolate. Do this in 30-second intervals in the microwave, stirring in between, until smooth. Be careful not to scorch it. Set it aside to cool down slightly.

Step 2: Cream the Butter and Sugars

• In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a handheld electric mixer, beat the 1 cup of softened unsalted butter, the ¾ cup of packed light brown sugar, and the ⅔ cup of granulated sugar on medium-high speed.
• Cream the mixture for 3-4 minutes, until it is light in color, fluffy, and has increased in volume. Scrape down the sides and bottom of the bowl as needed.

Step 3: Add the Eggs, Peppermint, and Melted Chocolate

• Reduce the mixer speed to medium and add the 2 room-temperature eggs, one at a time, beating well after each addition until it is fully incorporated.
• Beat in the 1 ½ teaspoons of pure peppermint extract.
• With the mixer on low, drizzle in the slightly cooled melted chocolate and mix until just combined.

Step 4: Combine Wet and Dry Mixtures

• With the mixer still on its lowest speed, gradually add the dry flour mixture to the wet ingredients in two or three additions.
• Mix only until the flour streaks have almost disappeared. Do not overmix.
• Remove the bowl from the mixer and use a rubber spatula to fold in the 1 ½ cups of chocolate chips or chunks until they are evenly distributed.

Part 2: Chilling the Dough (The Most Important Step)

Step 5: Chill the Dough

• The dough will be soft and sticky at this point. Cover the bowl with plastic wrap and transfer it to the refrigerator.
• Chill the dough for a minimum of 3 hours, but preferably overnight (up to 72 hours). This step is essential for developing flavor and preventing the cookies from spreading too much during baking.

Part 3: Baking the Cookies

Step 6: Prepare for Baking

• When you are ready to bake, preheat your oven to 350°F (175°C). Line two large baking sheets with parchment paper.
• Remove the cold dough from the refrigerator. It will be very firm.
• Using a medium cookie scoop (about 1.5 to 2 tablespoons), portion the dough into balls. You can roll them briefly between your palms to smooth them out.
• Place the dough balls about 2-3 inches apart on the prepared baking sheets.

Step 7: Bake to Perfection

• Bake the cookies, one sheet at a time, for 10-12 minutes.
• The edges of the cookies should be set, but the centers should still look slightly soft and underdone. This is the key to a chewy texture.
• Remove the baking sheet from the oven. If you like, you can gently press a few extra chocolate chips or pieces of Andes mints into the tops of the hot cookies for a beautiful, melty look.

Part 4: Topping and Cooling

Step 8: Add the Topping

• While the cookies are still hot on the baking sheet, place 1 or 2 Andes mints on top of each cookie.
• Let them sit for 3-5 minutes. The residual heat from the cookies will melt the mints.
• Once the mints are fully melted, use the back of a small spoon or a toothpick to gently spread the melted chocolate over the top of each cookie, creating a smooth, glossy layer or an artful swirl.
• If desired, sprinkle a tiny pinch of flaky sea salt on top of the melted mint chocolate.

Step 9: Cool Completely

• Let the cookies cool on the baking sheet for 10 minutes. The topping will still be soft.
• Carefully transfer the cookies to a wire cooling rack to cool completely. The mint chocolate topping will set and harden as the cookies cool. To speed up the setting process, you can place the cooling rack in the refrigerator for 10-15 minutes.